UNSPECIFIED (2005) Large-scale translocation reversal within the thylakoid Tat system in vivo. JOURNAL OF CELL BIOLOGY, 171 (2). pp. 281-289. ISSN 0021-9525

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Abstract

In vitro import assays have shown that the thylakoid twin- arginine translocase (Tat) system transports folded proteins in a unidirectional manner. Here, we expressed a natural substrate, pre-23K, and a 23K presequence green fluorescent protein (GFP) chimera in vivo in tobacco protoplasts. Both are imported into chloroplasts, targeted to the thylakoids, and processed to the mature size by the lumen-facing processing peptidase. However, the vast majority of mature GFP and about half of the 23K are then returned to the stroma. Mutations in the twin-arginine motif block thylakoid targeting and maturation, confirming an involvement of the Tat apparatus. Mutation of the processing site yields membrane-associated intermediate-size protein in vivo, indicating a delayed reversal of translocation to the stroma and suggesting a longer lived interaction with the Tat machinery. We conclude that, in vivo, the Tat system can reject substrates at a late stage in translocation and on a very large scale, indicating the influence of factors that are absent in reconstitution assays.

Item Type:	Journal Article
Subjects:	Q Science > QH Natural history > QH301 Biology
Journal or Publication Title:	JOURNAL OF CELL BIOLOGY
Publisher:	ROCKEFELLER UNIV PRESS
ISSN:	0021-9525
Date:	24 October 2005
Volume:	171
Number:	2
Number of Pages:	9
Page Range:	pp. 281-289
Publication Status:	Published
URI:	http://wrap.warwick.ac.uk/id/eprint/34363

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